use py37+ datetime.isoformat / .fromisoformat

since python 3.7, .isoformat() is usable IF timespec != "auto"
is given ("auto" [default] would be as evil as before, sometimes
formatting with, sometimes without microseconds).

also since python 3.7, there is now .fromisoformat().

src/borg/archive.py

@@ -644,8 +644,8 @@ Duration: {0.duration}
             "cmdline": sys.argv,
             "hostname": hostname,
             "username": getuser(),
-            "time": start.strftime(ISO_FORMAT),
-            "time_end": end.strftime(ISO_FORMAT),
+            "time": start.isoformat(timespec="microseconds"),
+            "time_end": end.isoformat(timespec="microseconds"),
             "chunker_params": self.chunker_params,
         }
         if stats is not None:

src/borg/constants.py

@@ -102,9 +102,6 @@ EXIT_WARNING = 1  # reached normal end of operation, but there were issues
 EXIT_ERROR = 2  # terminated abruptly, did not reach end of operation
 EXIT_SIGNAL_BASE = 128  # terminated due to signal, rc = 128 + sig_no
 
-# never use datetime.isoformat(), it is evil. always use one of these:
-# datetime.strftime(ISO_FORMAT)  # output always includes .microseconds
-# datetime.strftime(ISO_FORMAT_NO_USECS)  # output never includes microseconds
 ISO_FORMAT_NO_USECS = "%Y-%m-%dT%H:%M:%S"
 ISO_FORMAT = ISO_FORMAT_NO_USECS + ".%f"
 

src/borg/helpers/manifest.py

@@ -65,7 +65,7 @@ class Archives(abc.MutableMapping):
         id, ts = info
         assert isinstance(id, bytes)
         if isinstance(ts, datetime):
-            ts = ts.replace(tzinfo=None).strftime(ISO_FORMAT)
+            ts = ts.replace(tzinfo=None).isoformat(timespec="microseconds")
         assert isinstance(ts, str)
         self._archives[name] = {"id": id, "time": ts}
 
@@ -254,11 +254,11 @@ class Manifest:
             self.config["tam_required"] = True
         # self.timestamp needs to be strictly monotonically increasing. Clocks often are not set correctly
         if self.timestamp is None:
-            self.timestamp = datetime.utcnow().strftime(ISO_FORMAT)
+            self.timestamp = datetime.utcnow().isoformat(timespec="microseconds")
         else:
             prev_ts = self.last_timestamp
-            incremented = (prev_ts + timedelta(microseconds=1)).strftime(ISO_FORMAT)
-            self.timestamp = max(incremented, datetime.utcnow().strftime(ISO_FORMAT))
+            incremented = (prev_ts + timedelta(microseconds=1)).isoformat(timespec="microseconds")
+            self.timestamp = max(incremented, datetime.utcnow().isoformat(timespec="microseconds"))
         # include checks for limits as enforced by limited unpacker (used by load())
         assert len(self.archives) <= MAX_ARCHIVES
         assert all(len(name) <= 255 for name in self.archives)

src/borg/helpers/time.py

@@ -2,8 +2,6 @@ import os
 import time
 from datetime import datetime, timezone
 
-from ..constants import ISO_FORMAT, ISO_FORMAT_NO_USECS
-
 
 def to_localtime(ts):
     """Convert datetime object from UTC to local time zone"""
@@ -12,8 +10,7 @@ def to_localtime(ts):
 
 def parse_timestamp(timestamp, tzinfo=timezone.utc):
     """Parse a ISO 8601 timestamp string"""
-    fmt = ISO_FORMAT if "." in timestamp else ISO_FORMAT_NO_USECS
-    dt = datetime.strptime(timestamp, fmt)
+    dt = datetime.fromisoformat(timestamp)
     if tzinfo is not None:
         dt = dt.replace(tzinfo=tzinfo)
     return dt
@@ -26,22 +23,11 @@ def timestamp(s):
         ts = safe_s(os.stat(s).st_mtime)
         return datetime.fromtimestamp(ts, tz=timezone.utc)
     except OSError:
-        # didn't work, try parsing as timestamp. UTC, no TZ, no microsecs support.
-        for format in (
-            "%Y-%m-%dT%H:%M:%SZ",
-            "%Y-%m-%dT%H:%M:%S+00:00",
-            "%Y-%m-%dT%H:%M:%S",
-            "%Y-%m-%d %H:%M:%S",
-            "%Y-%m-%dT%H:%M",
-            "%Y-%m-%d %H:%M",
-            "%Y-%m-%d",
-            "%Y-%j",
-        ):
-            try:
-                return datetime.strptime(s, format).replace(tzinfo=timezone.utc)
-            except ValueError:
-                continue
-        raise ValueError
+        # didn't work, try parsing as a ISO timestamp. if no TZ is given, we assume UTC.
+        dt = datetime.fromisoformat(s)
+        if dt.tzinfo is None:
+            dt = dt.replace(tzinfo=timezone.utc)
+        return dt
 
 
 # Not too rarely, we get crappy timestamps from the fs, that overflow some computations.
@@ -106,7 +92,7 @@ def isoformat_time(ts: datetime):
     Format *ts* according to ISO 8601.
     """
     # note: first make all datetime objects tz aware before adding %z here.
-    return ts.strftime(ISO_FORMAT)
+    return ts.isoformat(timespec="microseconds")
 
 
 def format_timedelta(td):

src/borg/repository.py

@@ -656,7 +656,9 @@ class Repository:
         if self.append_only:
             with open(os.path.join(self.path, "transactions"), "a") as log:
                 print(
-                    "transaction %d, UTC time %s" % (transaction_id, datetime.utcnow().strftime(ISO_FORMAT)), file=log
+                    "transaction %d, UTC time %s"
+                    % (transaction_id, datetime.utcnow().isoformat(timespec="microseconds")),
+                    file=log,
                 )
 
         # Write hints file

src/borg/testsuite/archiver.py

@@ -249,6 +249,11 @@ def test_disk_full(cmd):
             assert rc == EXIT_SUCCESS
 
 
+def checkts(ts):
+    # check if the timestamp is in the expected format
+    assert datetime.strptime(ts, ISO_FORMAT)  # must not raise
+
+
 class ArchiverTestCaseBase(BaseTestCase):
     EXE: str = None  # python source based
     FORK_DEFAULT = False
@@ -1682,7 +1687,7 @@ class ArchiverTestCase(ArchiverTestCaseBase):
         repository = info_repo["repository"]
         assert len(repository["id"]) == 64
         assert "last_modified" in repository
-        assert datetime.strptime(repository["last_modified"], ISO_FORMAT)  # must not raise
+        checkts(repository["last_modified"])
         assert info_repo["encryption"]["mode"] == RK_ENCRYPTION[13:]
         assert "keyfile" not in info_repo["encryption"]
         cache = info_repo["cache"]
@@ -1701,8 +1706,8 @@ class ArchiverTestCase(ArchiverTestCaseBase):
         assert isinstance(archive["duration"], float)
         assert len(archive["id"]) == 64
         assert "stats" in archive
-        assert datetime.strptime(archive["start"], ISO_FORMAT)
-        assert datetime.strptime(archive["end"], ISO_FORMAT)
+        checkts(archive["start"])
+        checkts(archive["end"])
 
     def test_info_json_of_empty_archive(self):
         """See https://github.com/borgbackup/borg/issues/6120"""
@@ -2579,11 +2584,11 @@ class ArchiverTestCase(ArchiverTestCaseBase):
         list_repo = json.loads(self.cmd(f"--repo={self.repository_location}", "rlist", "--json"))
         repository = list_repo["repository"]
         assert len(repository["id"]) == 64
-        assert datetime.strptime(repository["last_modified"], ISO_FORMAT)  # must not raise
+        checkts(repository["last_modified"])
         assert list_repo["encryption"]["mode"] == RK_ENCRYPTION[13:]
         assert "keyfile" not in list_repo["encryption"]
         archive0 = list_repo["archives"][0]
-        assert datetime.strptime(archive0["time"], ISO_FORMAT)  # must not raise
+        checkts(archive0["time"])
 
         list_archive = self.cmd(f"--repo={self.repository_location}", "list", "test", "--json-lines")
         items = [json.loads(s) for s in list_archive.splitlines()]
@@ -2591,7 +2596,7 @@ class ArchiverTestCase(ArchiverTestCaseBase):
         file1 = items[1]
         assert file1["path"] == "input/file1"
         assert file1["size"] == 81920
-        assert datetime.strptime(file1["mtime"], ISO_FORMAT)  # must not raise
+        checkts(file1["mtime"])
 
         list_archive = self.cmd(
             f"--repo={self.repository_location}", "list", "test", "--json-lines", "--format={sha256}"
@@ -4058,7 +4063,7 @@ class ManifestAuthenticationTest(ArchiverTestCaseBase):
                             "version": 1,
                             "archives": {},
                             "config": {},
-                            "timestamp": (datetime.utcnow() + timedelta(days=1)).strftime(ISO_FORMAT),
+                            "timestamp": (datetime.utcnow() + timedelta(days=1)).isoformat(timespec="microseconds"),
                         }
                     ),
                 ),
@@ -4078,7 +4083,7 @@ class ManifestAuthenticationTest(ArchiverTestCaseBase):
                         {
                             "version": 1,
                             "archives": {},
-                            "timestamp": (datetime.utcnow() + timedelta(days=1)).strftime(ISO_FORMAT),
+                            "timestamp": (datetime.utcnow() + timedelta(days=1)).isoformat(timespec="microseconds"),
                         }
                     ),
                 ),